CCTV Storage Calculator: engineer's guide
CCTV storage is a product of bit rate, seconds per day, days of retention, and camera count. H.265 halves H.264 storage at the same quality.
Open the CCTV Storage calculator →
What this calculator does
The calculator returns required NVR storage capacity based on entered bit rate, camera count, and retention days.
Formulas used
- Per camera per day:
GB/day = (bitrate × 86400) / 8 × 10-9 - Total storage:
TBtotal = Ncameras × GB/day × days / 1000
Variables
- bitrate in Mbps
- Ncameras = active camera count
- days = retention period
Worked example
Scenario: 32 cameras at 4 Mbps H.265, 30-day retention.
- Per camera per day = 4 × 86400 / 8 = 43,200 MB = 43.2 GB
- Total = 32 × 43.2 × 30 / 1000 = 41.5 TB
- Add 20% index/margin → 50 TB usable
- Configure RAID 6 with hot-spare on enterprise-grade drives
Common mistakes to avoid
- Using H.264 bit rate for an H.265 system
- Missing motion-detection duty cycle reduction
- No RAID overhead accounting
- Ignoring audio channel storage
Frequently asked questions
H.264 vs H.265?
H.265 typically halves file size at same quality but needs faster decoding hardware.
Cloud vs on-prem?
On-prem for large systems (>32 cameras); cloud for small distributed sites with reliable bandwidth.
Standards and references
IEC 62676, IEEE 1220
Related tools on this site
Open the calculator that pairs with this guide: CCTV Storage Calculator.
Verification note
This guide is planning support only. Final design must be verified against the applicable project specification, authority requirements, manufacturer data, and the standards cited above. Consult a licensed engineer for construction-issue calculations.